Miles Magister from Dave Platt plan

[Andy Gates]

2nd cowl cheek added tonight.

Started on the rib capping, completed the upper panels inside of the ailerons. Rule in the photo below to give a sense of scale.

 

[Andy Gates]

Metalwork today as no flying possible.

 

Tail wheel made up. Both the wheel and the horn had to have sleeves made up to sort the size differences.

 

 

And from the inside. The leg has had the end peened over and pressed and CA'd into the top aluminium plate.

 

 

Now fitted to the tail.

 

 

Main undercarriage legs bent and fitted to the wing centre sections.

 

[Andy Gates]

And 1st time standing on her undercarriage

 

[Andy Gates]

Lower rear cowl former being laminated from 3 strips of 1/32" ply.

 

 

Trimmed down, sanded then attached to the fuselage.

 

[Andy Gates]

Added some sheeting and the cowl is looking reasonable. I did manage to knock a couple of chunks out of the sheeting so I have had to add some filler.

 

 

Also started on the fuselage sheeting around the cockpit area.

 

[Keith Billinge]

Wow!

Everything just looks so beautifully made and finished I clearly need a lot more building practice!

Nice one!

[Andy Gates]

Thanks for that Keith.

 

You should see her in the flesh tomorrow night.

[kc]

I have to agree with Keith B -it's looking very promising and the techniques should inspire others.   It's really just modern RC brought up to date with good old fashioned lightweight building methods.   Not too many signs of fancy materials,  nothing made from unobtainium, just 'proper' building methods.

 

I think the other club members will benefit from examining the model and maybe we will see more models built in this manner.    ( Andy- sorry I won't be there tonight but I hope to see the model some other time)

[kc]

I am sure there are plenty of other people watching this but all are too polite to ask questions.   As usual I am going to be 'Devils Advocate' and ask the awkward questions to tease out the info......

 

First I am going to ask about the tailwheel assembly - to me it looks as though the horn should be inside to connect with a pushrod and the bearing outside.  I am sure there is a reason for this being opposite!   Also is the alloy bearing in two parts, one fixed & one loose?

 

Second is the laminated cowl part.   I expected that it would take more than a few pins to keep the ply in shape.   Maybe the ply is cut with crossgrain so it all bends easily?

 

Third.  Are the u/c legs really just secured with just one u/c clamp per side?  Is it to allow the leg to come out easily in case of hard landing or just at an early stage before a second clamp is fitted?  It didn't look as though there was much length to the part into the block - is that just an illusion?

 

So the devil may be in the detail that we cannot quite see!

 

[Andy Gates]

Please all, always feel free to ask, I will never take offence.

The only stupid question is the one we don't ask - as we therefore don't understand.

 

KC,

 

Tailwheel is as you suggest, 2 parts of aluminium - one fixed to the wire of the tailwheel and one fixed to the airframe. The part connected to the airframe is top hat shaped to provide plenty of glue area with the top hat on the inside. Although it seems the wrong way round, the idea behind this is if something goes wrong the top hat may have the opportunity to break off the ply plate reducing damage to the airframe. Remember "build to fly and not to survive crashes", so this is a built in weak spot. If there is major vertical tail impact, the ply plate mounting strips will break way from the airframe too with little damage to repair.

The actuator / horn for the tailwheel is correctly fitted. I am going to be using pull pull wire for the rudder control so there is no pushrod to attach the tailwheel mechanism to. Therefore the tailwheel will be fitted with a pushrod (probably 2mm steel) to actuate from the rudder horn which make it all simple, lightweight and accessible for adjustment if necessary.

 

Laminated former for the cowl - the ply is very thin and was cut in the most flexible direction with the 2 outer layers cross grain. As in the picture, the pins held the shape of the ply while the other 2 layers were glued to the first one. Once dry the ply holds itself in place creating a quite strong and very light former. It is ideal as in the event of a landing gear failure type crash, the likely hood is that the cowl would come in for quite a bit of punishment.

This is the same technology used in some of the old Jaguar cars to produce seats believe it or not.

 

Talking of the U/C, yes the single clamp each side is only temporary - a second will be fitted near to where the leg enters the wing. The locations where both clamps are to be fitted have already been internally reinforced with some 1/8" ply. The beech torque blocks have been fitted to the inner ply reinforcements and the root ribs. Due to the angle of the torque rod in relation to the leg, they are actually quite long and point backwards into the wing.

[Andy Gates]

Quick picture of the plane assembled (some with masking tape) for last nights club night.

 

[Andy Gates]

Quick snap to show the length of the U/C leg that fits into the blocks inside the wing. Should be plenty for this light weight machine.

 

[John Lee]

Here's the prototype at the 1965 Nationals where it placed 4th. According to the report in Model Aircraft magazine the 'magnificent' model 'would certainly have fought for top honours' if not for mysterious fuel feed troubles.

 

[kc]

Thanks for explaining all the details Andy - I am sure this will help us all improve our construction.

 

Do you 'pre-curve' the balsa sheeting actually on the plane or on some other former?  

That 3.5 pound weight so far seems on track for a very light model when it's finshed.  

 

  ( some more of Andy's photos are on his own website and there are links to Andy's other models which are mostly much lighter than most of us would build.  Worth looking at those other models too )

 

 

 

[Andy Gates]

John,

 

Thank you for that post. I had not seen that image before - I was not aware just how good Dave Platts model was, nor its age.

 

Mine will certainly not be to his standard and I am dropping scale details in favour of simplicity, light weigh and robustness.

Mine will not sport the metal cowling, instead it will be film covered balsa.

The u/c legs are plain wire which may be shrouded rather than the true legs which DP has detailed. Same with the tail wheel.

 

I was wondering if I had got the leg length wrong as it looks really gangly, but that picture confirms that I have it about right.

Cockpit detail will also be left out as it will not be seen while in flight.

 

KC,

 

My pleasure to detail what I am doing. Everyone builds differently so this is how I do it - not necessarily the best, fastest or the only way.

At club night, comments were made about the join lines having no gap.

There is nothing special I do to achieve this, straight line joins are glued then the sheets pulled together with tape and left to dry.

 

As to the pre-curve, the answer is sometimes.

The cockpit cover was not pre-curved as it is a fairly straight uniform curve so not necessary.

The rear sections from cockpit to tailplane, definitely!

Reason is this is a tapering curve with a bit of compound curve added too.

In this instance the balsa was wetted on the outside, then taped to a piece of 3" guttering downpipe and left to set and dry off.

The compound is then dealt with by cutting a knife thickness slot in the wood and allowing the edges to overlap each other while held in place with tape. once the curve is taken the overlap is removed, edges glued and all taped down to set.

[kc]

This started out as a Dave Platt design but it now seems that its really more Andy's design at this size and type of construction.    At least we can say it's an Essex design!

Dave Platt is probably better known in USA than here in his own country -Britain - but he was a member of the Dagenham MAC in Essex in the 1960's.   There is some info about Dave Platt here.  One thing stated is that he designed the models for the film 'Battle of Britain' which was largely filmed at North Weald.

[Andy Gates]

To be fair, as Trevor said earlier, it is more Pettigrew than Platt.

 

I wanted a Magister but around the size of my Chipmunk.

The Dave Platt plan was good but 10lbs is way too much for me.

So I applied Ivans principles to Daves plan blown up to 120%.

 

To me, I can't take any credit as i have designed nothing. Adapted yes, designed no.

 

Dave's prototype that he used in the nationals is as old as I am!

[Andy Gates]

A little weekend update.

 

 

Ailerons added after adding reinforcements for the horns and top surface sheeted, the servos and the mounting plates sanded to fit.

 

 

Top sheet complete but headrest fairing to be added.

Edited March 13, 2022 by Andy Gates
missed a bit

[Andy Gates]

A few things happening recently.

 

Aileron pushrods have been made and fitted, they just need tweaking when the radio is ready to go.

 

Ordered some radio hardware which turned up yesterday, radio actuated switch for the LED lights, lipo sensor and GPS sensor to give me telemetry which is useful for training.

 

Added the Magister to my radio, adjusted the programming for the surfaces and the training set up and detected the telemetry after updating the receiver firmware and rebinding it.

 

Tonight I have built and fitted the hump behind the rear cockpit.

 

 

The white patch is CA as the wood was trying to split while I was sanding it.

 

Hopefully tomorrow the pilot and the small split pins I have ordered for the hinges will turn up.

[Andy Gates]

Look what was at home for me when I got in....

 

 

He seems to fit nicely although I may have to lift him a little more.

[Andy Gates]

Why is it all the little bits to do consume so much time?

 

Receiver is mounted and antennae placed in position, short aileron extensions made and ailerons tested.

LED's rigged up and wired together and to the switch and tested.

GPS unit fitted in place.

Pilot fitted to his mount and that is screwed in place with a stiffener underneath to stop him nodding.

 

Current weight is 1915g or 4lbs 3.5oz

 

So what is left to be done?

Fin and rudder to be completed and sanded down, fin to be fitted to fuselage.

Rudder to be hinged and control horns fitted.

Finish off battery cover which is about 3/4 done.

Sand all LE to shape.

Add anti spin strakes.

Sand tailplane to section.

Final sanding all over.

Cover & detail.

FLY!

[Andy Gates]

A bit more done and a photo or 2.

 

Fin and rudder fitted but no controls yet for it.

Lights are on in the picture.

 

 

And from behind..

 

 

And finally the tail wheel steering mechanism which still needs a little fettling.

 

[Murat Kece 1]

looks so clean. Excellent.. as if you painted the wood?

[Andy Gates]

Just worked out why it appears so clean - I use flash on the camera as the light is so poor at the moment.

 

 

Adding lower wing fillet sheeting, 1/32" ply and fixed with Gorilla Glue which expands so it will hopefully force the ply against the wing as it sets as well as fill any gaps.

Wing has been covered with cling film prior to the glue being added.

[Andy Gates]

Been flying so not too much done on the Magister this weekend.

 

I had another weigh in which came in at 1963g or 4lbs 5.25oz.

 

Ran a power check too.

 

WOT static on 3S gave 572w, 4S gave 928w so that is 132w/lb or 214w/lb so no shortage of power.

 

Just have to get it finished now.